Propeller



Set, 6, 1932. s AT 1,875,598

PROPELLER 5 Sheets-She et 1 Filed Sept. 17, 1929 Gttorncg Sept. 6, 1932. HEATH 1,875,598

PROPELLER Filed Sept. 17, 1929 3 Sheets-Sheet 2 a \llll Uuucr inventor V a gm M 2mm V 1327 Gttorncg Sefat. 6, 1932. S HEAT 1,875,598

PROPELLER Filed Sept. 17. 1929 s Sheets-Sheet z 2 j i I :3nn'entor mph Bu M Gttorneg Patented 6, 1932 UNITED STATES.

PAT NT OFFICE SPENCER HEATH, OII' BALTIMORE. MARYLAND, ASSIGNOR TO THE AMERICAN PRO- PELLEB COMPANY, OF BALTIMORE, MARYLAND, A CORPORATION MARYLAND PBOPELLEB Application as September 17, 929. ser l no. 393,241.

This invention relates to propellers and more. particularly to-variable pitch propellers.

One of the objects of the present invention is to.provide nove1 means for changing the pitch of the propeller blades, saidmeans being so Constructed as to be operable at any ti ple during the normal operation of the prope er.

Another object of the invention ,is to provide novel power operated means for varying the pitch of the propeller blades, the power for actuating said means being derivable from the source of power employed for rotating the propeller and being combined with suitable manually operable control means.

v changing means embo ng non rotatable friction elements, which l tter are not in engagement with any rotatable part exceptdurmg the pitch changing operation.

A further object is to rovide novel means for positively limiting t e movement. of the pitch changing means at two positions corresponding to the extremes of high and low pitch of the blades.

Another ob'ect is to provide novelmeans for holding t e blades in an adjusted posi- Another object is to provide novel pitch tion whereby any tendency of the blades to I have been moved to a maximum position.

creep away from said position is positively prevented.

Another object is to provide releasing means for the pitchchanging actuating mechanism whereby the operating energy will not be unduly prolonged after the blades A further object includes the provision of flight adjustable pitch changing mechanism incombination with blade anchorages or mountings of the type now in common use.

The above and other objects will appear more fully hereafter .the detailed description wherein there is described one embodiment of the present invention, the latter being.

- illustrated in the accompanying drawings? It is to expresslyfunderstood, however, that'the drawings are for purposes of illustration only and are not designed'as a definition of the limits;o'f the invention, refchanging mechanism ,bein shown in axial section on the line H of .ig." 3';

Fig. 5 is "a detailed perspective view of a portion of one type of means which may be employed for actuating the friction elements of the apparatus;

Fig. 6 is a transverse view in section illustrating one manner in which the propeller blades may be mounted in the hub; and

Fig. 7 is a detailed perspective viewof a portion of the blade mounting means shown in Fig. 6.

In the form shown, the propeller is of the aircraft type adapted to be actuated by an internal combustion engine a portion of the crank case of the latter being shown at 8. The crank shaft 9 of the engine, or an extension thereof, has rigidly-secured thereto a hub or barrel 10 in.which are rotatably mounted'a pair of blades 11. As illustrated. the blades are of the metaltype and are so mounted as to be adjustable to the desired pitch positions during flight. Where it is desired to employ metalblades of the type now in use, thebutts of the blades are surrounded by ferrules 12*(Figs. 6 and 7) which are rotatably mounted within hub v10 and which are provided at their inner ends with internal gears 18. Preferably the butt of each blade is surrounded 'y a laggi 14 which is originally made in one piece 51:5 is then split longitudinally into two halves in order that the blade vbutt may be positioned therein. The blade with the ferrule assembled thereon and with "the lagging 14 interposed therebetween and threaded intothe ferrule is inserted into the openend of hub 10 and retained therein by means of a thrust ring 15 threaded in the open end of the hub. A suitable antifriction bearvery firmly between the ferrule 12 and the blade butt. To this end the diameters of the blade butt or anchorage and the lagging are such that it is just possible to screw the lagging into the ferrule with great force. Preferably the outer end of the ferrule carries set screws 17 which are threaded into the lagging 14 to prevent unscrewing of the latter and to compress it firmly between the ferrule and the blade anchorage.

Eositioned within hub 10 and in operative engagement with gears 13 are two sets of nonreversible, duplex worm gear trains, one set for each blade, for locking the blades in adjusted position and for altering the pitch of the blades. These gear trains, which may be similar to those illustrated and described in my Patent No. 1,589,17 4, dated June 15, 1926,

include a pair of worm shafts 18 which are disposed substantially parallel to engine shaft 9 and project at their inner ends through the hub 10. The projecting end of each shaft 18 carries a pinion 19 constituting one element of the gear trains referred to above, the opposite ends of said gear trains being constituted by pinions 20 in driving engagement with I the internal gears 13.

Means are provided for rotating pinions 19 either direction whereby the pitch of the blades 11 may be varied at any time during the normal operation of the propeller. For

7 this purpose, each of the pinions 19 mesh with an external gear 21 and also with an internal gear 22,,said gears being concentrically disposed relative to each other and to shaft 9. The external spur gear '21 is rigidly connected in any suitable manner to a sleeve 23 which is freely journaled on shaft 9 and constitutes ,the hub of an external brake drum 24 4) said drum being laterally displaced rom gear 21. ,Mounted for free rotation on sleeve 23 is the hub portion 25 of an internal brake drum 26 to which is rigidly secured in any suitable manner the internal gear 22. Hub 25 .of the drum 26. is mounted intermediate gear 21 and drum 24 whereby the drums and %ears 21 and 22 are concentrically disposed.

y this arrangement it will be apparent that as long as the brake drums and gears 21 and 22 rotate in unison, no rotary movement will be imparted to pinions 19 about .the axes of worm shafts 18. If one of said drums is held against rotation, however, the relative. rotar movement of the drums is e'lfective throu gears 21 and 22 to rotate P11110118 19where y drums 24 and 26 against rotation. As shown,

said means comprises a pair of brake shoes 27 (Fig. 3) which are provided with suitable lining on the opposite faces thereof whereby said brake shoes are adapted for engagement with either of the brake drums 24 and 26. The opposite ends of the two shoes are anchoredas at 28 to suitable pins carried by and projecting outwardly from the face of a circular plate '29 that is rigidly secured in .any suitable manner to the outer end of crank case 8. The movable end of each of the brake shoes 27 is secured to a rectilinearly movable pin 30 whereb said shoes may be moved inwardly into frictional engagement with drum 24 or outwardly into engagementwith drum 26.

Novel means are provided for moving brake shoes 27 into operative engagement with the desired brake drum and in the form shown, said means areof the hydraulic type. To this end pins 30 are rigidly attached to collars 31 which are fixedly secured to piston rods-32 adapted-to be actuated by pistons 33 which are mounted to reciprocate in c linders 34 that are mounted in any suita 1e manner on plate 29. In the form shown, cyl- .inders 34 are carried by housings 35 of tubular form, said housings being secured by mounting plates 36 to the inner face of the circular plate 29. Each housin 35 is provided with a pair of diametrica ly disposed longitudinal slots into which extend lugs 37 that are formed on collars 31 whereby the latter are guided during the reciprocation of the same within the housings 35. Interposed between the opposite faces of the collar 31 and suitable abutments carried by housing 35 are a pair of coil springs 38, each of which surrounds piston rod 32 within housing 35. The springs 38 normally hold collar 31 in such" a position that'the brake shoe attached thereto is retained out of engagement with the brake drums 24 and 26. I

Means are provided for moving the pistons 33 in either direction within the cylinders 34 and in the form shown said means is ofthe hydraulic type that may include a manually actuated pump 39 (Fig; 1) suitably mounted in any convenient position such as the instrument board of theaircraft. Actuation of the plunger 40 of pump 39 is effective to transmit fluid pressure through one or the other of awhen the pump plunger 40 is move in one.

posite directions Within their respective c linders 34 and the brake shoes 37 will there y be moved into operative engagement with one or the other of brake drums 24 and 26 whereby relative rotary movement will be im arted to gears 21 and 22 and the pitch of the lades will be varied. It will be noted that movement of piston 33 in one direction is effective through collar 31 to compress one of the springs 38 and that whenever the collars are moved from normal position springs 38 tend to restore said collars to a position such that the brake shoes 27 are moved to an intermediate position out 'of engagement with the brake drums.

Preferably the apparatus of the present invention is so constructed that the fluid pressure cannot be indefinitely sustained thus rendering it impossible'to hold the brake shoes in engagement with the brake drum for any great length of time. To this end the piston 46 of pump 39 may be provided with a vent 47 or said piston may be loosely fitted within the pump cylinder. Pistons 33 may also be provided with suitable vents and it will thus beapparent that when the fluid pressure is relieved on said pistons -the compressed springs 38 will return piston rods 32 and collars 31 to normal position whereby the brake shoes are returned to the position illustrated in Fig. 3 and the brake drums are released for rotation in unison, it being understood that the blades are retained in adjusted position by the worm gearing referred to above.

Means are preferably provided for ositively limitin the range of the pitch ad ustment of the lades. It will be noted that when one of the brake drums is held against rotation pinions 19 are rotated about the axes of shafts 18 and the other brake drum rotates relative to the stationary one and if this relative rotation is of sufiicient extent it is eflective to move a pair of stops 48 and 49 into positive engagement whereby further relative rotation of the brake drums and henceffurther adjustment of the pitch of the blades is prevented. Stop '48 is secured tothe inner face of the web of drum 26 in a position such as to engage stop 49 secured to drum 24. In the form shown, the stops are attached tothe respective drums by means of screws which pass through openings in the stops lined with suitable yielding material, such as-rubber, which absorbs the shock of engagement. As shown in Fig. 3 stops 48 and 49 are in abutting engagement with the blades in maximumadjustment at one end of the pitch range. Any effort to effect a further change in the same direction will merely result in slippage between the brake shoes and the enga ed brake drum. Adjustment of the itch of t e blades towards the opposite end 0 the range will cause stops drums' are released and may 48 and 49 to move apart until they again come into abutting engagement at the opposite ends thereof at which time the blades will .be in the maximum position of adjustment at the other end of the range.

Means are preferably provided for posi-- 'tively locln'ng the'two brake drums together at one extreme pitch position. In the form shown, brake drum 26 has pivoted to the web thereof, as at 50, '(Fig. 3), a pawl 51 adapted to engage stop 49 carried by drum 24 when said stop is in abutting engagement with stop 48, whereby said stops are positively locked against angular movement away from .eachother. Stop 49, during its movement toward stop 48, slides freelynnderneath pawl 51 but centrifugal force'is thereafter effective to move the end of the pawl into locking engagement with the adjacent end of stop 49, the outward movement of the pawl being limited by mezfns of a pin 52. A roller 53 is secured to pawl 51 in such a position that )when the latter is in looking engagement with stop 49 the roller (projects beyond the outer periphery of brake drum 24 and into the plane of the adjacent brake shoe 27. When said brake .shoe is moved inwardly to engage drum 24 it acts through roller 53 to move pawl 51 out of locking engagement with stop 49,'whereby said brake be rotated to change the pitch of the blades to the 0pposite end of the range. There is thus provided a variable pitch propeller which is simple and compact in structure and which is inexpensive to manufacture and install. The pitch of the blades may be quickly changed while the propeller is in operation and while the craft on which it is mounted is at rest or in motion. In thebeing preferably controlled by manually operable means which are readily accessible to the operator of the vehicle. The construction is such that standard metal blades may be readily employed in the event thatit is not desired to employ wooden or other'types of blades. The brake shoe applying mechthe brake drum for any great length of time thereby avoiding excessive wear of the parts anismis so constructed that it is-impossible f to hold the brake shoes in engagement withdue to carelessness on the part of the operator. I

I The fluid pressure means are simple and dependable in operation and it'will be understood that the vents may be Omitted from the pistons 33. The non-reversible worm gearing constitutes means for holding the lades in adjusted position and it'will therefore be seen that the positive locking means 'may be omitted in certain installations.

While only one embodiment of the invention has been illustrated in the drawings, it will be apparent to those skilled in the art that various changes may be made in the construction and arrangement of parts'without departing from the invention. Reference will therefore be had to the appended claims for a definition of the limits of said invention.

What is claimed is:

1. In combination with a propeller adapted to be actuated by'a' power shaft and embodying a variable pitch blade, means for varying the pitch of said blade including a pair of concentrically mounted gears, a pair of brake drums arranged in co-planar relation and op-' eratively connected to said gears and fluid pressure means for selectively holding .said drums against rotation.

- 2. 'In combination with a propeller having a pitch adjustable blade, means for adjusting the pitch of said blade including a shaft for rotating the propeller, gearin operatively connected to the blade, a pair 0 brake drums operatively connected to the gearing and normally adapted for rotation in unison with said shaft, a brake shoe, means for selectively moving said shoe into engagement with one or the other of said drums to hold the engaged drumagainst rotation .and actuate the gear mechamsm to change the pitch of the lade, and

. means associated with said drums for positively limiting the pitch adjusting movement thereof.-

3. In combination with a propeller havinga pitch adjustable blade, means for adjusting the pitch of said, blade including a shaft for rotating said propeller, gearingcarried by the propeller and having" operative engagement,

with said blade, friction drums operatively connected to said gearing and adapted to rotate in unison with said shaft, means for selectively holding one of said drumsagainst rotation whereby relative, rotary movement is imparted to the drums from said shaft, and stops carried by said drums and movable into abutting engagement to positively limit the relative rotation of said drums. q

'4. In combination with a propeller having pitch adjustable blades, a shaft for rotating said propeller, and means for adjusting the pitch of said blades including a pair of brake drums operatively connected to the shaft and blade, said drums being adapted to rotate in unison with said shaft, a brake shoe adapted for selective engagement with either of said engaging position.

drums to hold the engaged drum against rotation, means for actuating said shoe, and

means independent of said actuating means for restoring the shoeto normal, non-engagmg pos1t1on.

5. In combination with a propeller having pitch adjustable blades, a shaft for rotating said propeller, and means for varying the pitch of said blades including'a pair of brake members operatively connected to said shaft and blades, and a member positioned between said brake members and selectively movable into engagement-with either ofthe same to.

hold the engaged member against rotation.

6. In combination with a propeller having pitch adjustable blades, a shaft for rotating said propeller, and means for varying the pitch of said blades including fluid pressure means, friction means actuated by the fluid pressure means, and means for automaticalreleasing the pressure generated by the ffilid pressure after a predetermined interval of time.

7. In combination with a propeller havingpitch adjustable blades, a shaft for rotating said propeller, means actuated by said shaft for varying the pitch of said blades, said means including a brake shoe, means for con-- trolling the operation of said brake shoe,

means for locking the blades in adjusted position, said means being adapted to be positively released by said brake shoe, and means for returning the brake shoe to normal, non- 8. In a variable pitch propeller, a hub, a

ferrule rotatably mounted in said hub, a

blade, a two-part lagging interposed between the blade and ferrule, said lagging having threaded engagement with said ferrule and being firmly compressed between the latter and the blade, a thrust ring carried by thehub and an anti-friction bearing interposed between said thrust ring and ferrule.

9. In combination with a propeller having pitch adjustable blades, means for adjusting the pitch of said blades including a shaft for Irotating the propeller, friction drums opmeans for returning said member to normal inactive position after operation of said flu d ressure means.

11. n combination with a propeller having .pitch adjustable blades, means movable to effect a change in pitch ofthe blades, fluid pressure means for moving said first-named r I means and means for returning said firstnamed means to normal inactive position after operation of said fluid pressure means and irrespective of prolonged operation of the latter.

12. In combination with a propeller having pitch adjustable blades, a shaft for rotating saidpropeller, and means for varying the pitch of said blades including a pair of brake drums arranged in co-planar relation and operatively connected to said shaft and specification.

blades, brake shoes for holding said drums against, rotation and fluid pressure means for moving said shoes into engagement with said drums. v

In testimony whereof I have signed this SPENCER HEATH. 

